高原环境对兔泪液指标及相关解剖结构的影响

Effects of plateau environment on tear indexes and related anatomical structures of rabbits

摘要:

目的：探讨高原低压缺氧环境对兔泪液指标及相关解剖结构的影响。

方法：选取18只健康新西兰兔，随机分为高原组和对照组，每组9只18眼。高原组饲养于西北特殊环境人工实验舱，模拟海拔6 000 m低压缺氧环境； 对照组饲养于常压常氧的清洁动物房。分别于干预前、干预3、7 d，2、4 wk采用RHCT-1角膜地形图仪干眼综合分析系统检测泪河高度、泪膜破裂时间，并采用泪液分泌试验测量泪液分泌量，同时利用拉曼光谱分析高原环境干预前后泪液成分的变化。干预4 wk采用苏木素-伊红(HE)染色观察下睑结膜、角膜、泪腺、哈氏腺的组织病理学变化，采用免疫组织化学法检测结膜组织中黏蛋白5AC(MUC5AC)的表达。

结果：与对照组相比，高原组兔泪液分泌量、泪河高度、首次及平均泪膜破裂时间自干预3 d开始明显下降，且随观察时间的延长有显著差异(P<0.05)； 干预2 wk开始上述各指标增加。干预4 wk，高原组兔泪液成分中蛋白质、脂质含量较干预前增多，核酸含量较干预前减少，且与对照组相比，高原组兔角膜基质水肿增厚，结膜杯状细胞数量增多，MUC5AC表达水平升高，泪腺上皮细胞胞浆萎缩扁平，腺腔扩大，哈氏腺无明显破坏性改变。

结论：急性高原环境可破坏兔眼表稳态，使泪液分泌量下降，泪膜稳定性降低，但在一定时间内随着对低压缺氧环境的习服，机体发生代偿，可在一定程度上增加泪液分泌量，恢复泪膜稳定性。

Abstract:

AIM: To investigate the effects of hypobaric hypoxia in plateau on tear indexes and related anatomical structures in rabbits.

METHODS: A total of 18 healthy New Zealand rabbits were selected and randomly divided into plateau group and control group, with 9 rabbits(18 eyes)in each group. The plateau group was housed in the Simulated Climate Cabin for Special Environment of Northwest of China, simulating hypobaric hypoxia at an altitude of 6 000 m. The control group was housed in a clean animal room with atmospheric pressure and oxygen. Changes in the tear meniscus height and non-invasive tear break-up time were detected by using RHCT-1 corneal topographer dry eye comprehensive analysis system, changes in tear secretion was measured by Schirmer Ⅰ test, before intervention and on the 3, 7 d, 2 and 4 wk. Meanwhile, the changes in tear composition before and after intervention in the plateau environment were analyzed using Raman Spectroscopy. The histopathological changes of the lower lid conjunctiva, cornea, lacrimal gland, and Hardarian gland were observed by hematoxylin-eosin(HE)staining after 4 wk of intervention, and the expression of mucin 5AC(MUC5AC)in conjunctiva was detected by immunohistochemistry.

RESULTS: Compared with the control group, Schirmer Ⅰ test, tear meniscus height, first and average non-invasive tear break-up time in the plateau group decreased significantly since 3 d, and the difference was significant with the extension of observation time(P<0.05). The above indexes increased from 2 wk. After 4 wk of intervention, the protein and lipid content of the tear composition of rabbits in the plateau group increased, and the nucleic acid content decreased compared with the pre-intervention period. Compared with the control group, rabbits in the plateau group showed thickening of corneal stromal edema, an increase in the number of conjunctival cup cells, increase in the level of expression of MUC5AC, an increase in the level of expression of MUC5AC, an atrophy and flattening of cytoplasm in lacrimal epithelial cells, an enlargement of glandular lumen, and no obvious destructive changes in the Hardarian glands.

CONCLUSION: Acute plateau environment can destroy the homeostasis of rabbit ocular surface, so that the tear secretion and the tear film stability decreases, but within a certain period of time, rabbits undergo compensation with the habituation to the hypobaric hypoxia environment, which can increase the tear secretion to a certain extent and restore the tear film stability.